As indicated by the title, two separate lines of investigation are being carried out. Investigations designed to study the ontogeny of immune responses in embryos and the relation of immunity to pathology in malaria infections have indicated that immunopathological responses may be produced in malarious chicken embryos by introduction of hyperimmune serum but not by transfer of spleen cells from hyperimmune birds to chorio-allantois. The intravenous route will now be employed in an effort to demonstrate adoptive immunity. A comparison of the plasma proteins already demonstrated in malarious and non-malarious embryos with those in the neonate chick will be made. The evidence adduced from some of the above experiments that the merozoites of the avian malariaparasite, Plasmodium gallinaceum, depart the erythrocytes without destruction of the host cell will be sought utilizing the scanning electron microscope. Adaptive potential of this same species of malaria will be studied in efforts to enhance such potential. Further evidence of dissemination of th trypanomatid infecting members of the plant family Asclepiadaceae, Phytomonas elmassiani, through the aegis of migration of its hemipteron, Oncopeltus fasciatus, will be sought. Surveys of plants and bugs for levels of infection in the months of January, February, and March in Palm Beach County, Florida will be made. From these data we may be able to establish a mathematical model for spread of this parasite each year to the northern tier of the United States.